356 research outputs found
Complete solutions of a family of quartic Thue and index form equations
No full textContinuing the recent work of the second author, we prove that the diophantine equation fa(x; y) = x 4 \Gamma ax 3 y \Gamma x 2 y 2 + axy 3 + y 4 = 1 for jaj 3 has exactly 12 solutions except when jaj = 4, when it has 16 solutions. If ff = ff(a) denotes one of the zeros of fa(x; 1), then for jaj 4 we also find all fl 2 ZZ[ff] with ZZ[fl] = ZZ[ff]. 1991 Mathematics Subject Classification. Primary 11D25, 11D57, 11R16, 11Y50. y Key words and phrases: Thue equation, index form equation, linear forms in the logarithms of algebraic numbers, distributed computation z Research partly done while the author was a visiting professor at the Fachbereich 14 - Informatik, Universitat des Saarlandes. 1. Introduction Let a 2 ZZ and f a (x; y) = x 4 \Gamma ax 3 y \Gamma x 2 y 2 + axy 3 + y 4 = x(x \Gamma y)(x + y)(x \Gamma ay) + y 4 : In a recent paper, Petho [8] proved that for 3 jaj 100 and jaj 9:9 \Theta 10 27 the Thue equation f a (x; y) = 1 (1) has only ..
Gipsy music from Hungary
No full text1.Csárdás /Vittorio Monti +2.The cock is crowing = Szól a kakas már /author unknown ;I tie up my horse = Megkötöm lovamat /author unknown ;It was a long time ago = Jaj, de nagyon régen volt /János Bihari +3.Never chide me = Ne szidjatok soha engem /Tibor Kalmár ;She who was my all = Aki nekem mindenem volt /Tibor Kalmár ;I am just telling you = Csak úgy mondom magának /Mihály Sallay ;My lover is from the other side of the Danube + A szeretőm dunántúli /Tibor Kalmár - István Fehér ;I am in a good mood = Jó kedvem van nékem /Jenő "Sügöle" Parády +4.I hobbed my white socked horse = Békót tettem kesely lovam lábára /Gábor Vas - Mihály Tompa +5.The stalk of the tender violet broke = Gyönge violának letört az ága /Pista Dankó - Sándor Endrődi ;My velvet high hat = Török bársony süvegem /author unknown ;Csinom Palkó /author unknow
Synergy and Group Size in Microbial Cooperation
No full textMicrobes produce many molecules that are important for their growth and development, and the exploitation of these secretions by nonproducers has recently become an important paradigm in microbial social evolution. Although the production of these public-goods molecules has been studied intensely, little is known of how the benefits accrued and the costs incurred depend on the quantity of public-goods molecules produced. We focus here on the relationship between the shape of the benefit curve and cellular density, using a model assuming three types of benefit functions: diminishing, accelerating, and sigmoidal (accelerating and then diminishing). We classify the latter two as being synergistic and argue that sigmoidal curves are common in microbial systems. Synergistic benefit curves interact with group sizes to give very different expected evolutionary dynamics. In particular, we show that whether and to what extent microbes evolve to produce public goods depends strongly on group size. We show that synergy can create an "evolutionary trap" that can stymie the establishment and maintenance of cooperation. By allowing density-dependent regulation of production (quorum sensing), we show how this trap may be avoided. We discuss the implications of our results on experimental design.</p
The Lidar system of the Pierre Auger Observatory
No full textThe Pierre Auger Observatory in Malargue, Argentina, is designed to study the origin of ultrahigh energy cosmic rays with energies above 10(18) eV. The energy calibration of the detector is based on a system of four air fluorescence detectors. To obtain reliable calorimetric information from the fluorescence stations, the atmospheric conditions at the experiment's site need to be monitored continuously during operation. One of the components of the observatory's atmospheric monitoring system is a set of four elastic backscatter lidar stations, one station at each of the fluorescence detector sites. This paper describes the design, current status, standard operation procedure, and performance of the lidar system of the Pierre Auger Observatory. (c) 2007 Elsevier B.V. All rights reserved
A survey of attitudes towards patient substance abuse/addiction in the emergency center.
No full textIncludes abstract.Includes bibliograpical references.Hospitals across South Africa are inundated with patients suffering from conditions associated with substance abuse. It is inevitable that contact with health services be made through an emergency centre (EC) at some point. This study aims to assess the exposure and attitudes of emergency physicians to substance abuse and addiction in major South African academic ECs. A prospective survey based on the Substance Abuse Attitude Survey (SAAS) was conducted in a convenience sample of eighty five emergency physician registrars and junior consultants in Cape Town, Gauteng, Limpopo and KwaZulu Natal. Respondents were targeted during academic meetings and by post
Metabolic regulation of excitation - contraction coupling in human airway smooth muscle cells
No full textAsthma is a chronic airway disease with a complex etiology, characterized by repeated exacerbations, bronchial spasm, and airway remodeling. Airway hyperresponsiveness (AHR) is the salient clinical feature of asthma, which consists of elevated maximal responses and sensitivity to contractile agonists. Human airway smooth muscle (HASM) cells play a pivotal role in mediating AHR. In HASM cells, interactions of contractile agonists with their membrane receptors elicit intracellular signaling events that culminate in cell shortening. These signaling cascades, collectively called excitation-contraction (EC) coupling, are amplified in asthma to mediate AHR in asthma. Numerous studies have demonstrated that metabolic dysfunctions are associated with the development of asthma and AHR. The purpose of this dissertation was to investigate the mechanistic link between cellular metabolism and airway hyperresponsiveness, through a step-by-step dissection of cellular signaling pathways in HASM cells. Obesity, a hallmark of metabolic syndrome, demonstrates distinct metabolic profiles in various cell types, including altered lipid metabolism, glucose metabolism, and energy biosynthesis. Additionally, obesity aggravates asthma by enhancing AHR and attenuating response to treatment. However, the precise mechanisms linking obesity and asthma remain unknown. The findings of this dissertation demonstrate that obesity induces a distinct metabolic profile of HASM cells, characterized by changes in glycolysis and citric acid cycle in untargeted metabolomics screening. Obese donor-derived HASM cells also showed elevated glycolysis rates, glycolytic capacity, and glycolytic enzyme expression. Therefore, we sought to examine the effect of glycolysis on AHR in human small airways. The inhibition of glycolysis attenuates agonist-induced EC coupling in HASM cells and bronchoconstriction in human precision-cut lung slices (hPCLS). Subsequent mechanistic studies demonstrated that decreased cellular ATP and phosphorylation of various proteins in the EC coupling pathway appeared to drive this bronchoprotective effect of glycolysis inhibition. In addition, the effect of another essential component of cellular metabolism, free fatty acids, on EC coupling was investigated in HASM cells. Activation of free fatty acid receptor 1 (FFAR1) attenuated agonist-induced myosin light chain (MLC) phosphorylation and cell stiffness in HASM cells. Taken together, this dissertation research provides novel insights into the metabolic regulation of AHR in airway smooth muscle and helps to potentially identify new therapeutic targets for asthma.Ph.D.Includes bibliographical reference
Using fuzzy logic modelling to simulate farmers’ decision-making on diversification and integration in the Mekong Delta, Vietnam
No full textTo reveal farmers’ motives for on-farm diversification and integration of farming components in the Mekong Delta, Vietnam, we developed a fuzzy logic model (FLM) using a 10-step approach. Farmers’ decision-making was mimicked in a three-layer hierarchical architecture of fuzzy inference systems, using data of 72 farms. The model includes three variables for family motives of diversification, six variables related to component integration, next to variables for the production factors and for farmers’ appreciation of market prices and know-how on 10 components. To obtain a good classification rate of the less frequent activities, additional individual fine-tuning was necessary after general model calibration. To obtain the desired degree of sensitivity to each variable, it was necessary to use up to five linguistic values for some of the input and output variables in the intermediate hierarchical layers. Model’s sensitivity to motivational variables determining diversification and integration was of the same magnitude as its sensitivity to market prices and farmers’ know-how of the activities, but less than its sensitivity to labour, capital and land endowment. Modelling to support strategic decision-making seems too elaborate for individual farms, but FLM will be useful to integrate farmers’ opinions in strategic decision-making at higher hierarchical levels.Infrastructures, Systems and ServicesTechnology, Policy and Managemen
Soil burial reduces decomposition and offsets erosion-induced soil carbon losses in the Indian Himalaya
No full textThis is the author accepted manuscript. The final version is available from Wiley via the DOI in this record The data that support the findings of this study are openly available in Figshare at https://doi.org/10.6084/m9.figshare.16903240.v1.The extent to which soil erosion is a net source or sink of carbon globally remains unresolved but has the potential to play a key role in determining the magnitude of CO2 emissions from land-use change in rapidly eroding landscapes. The effects of soil erosion on carbon storage in low-input agricultural systems, in acknowledged global soil erosion hotspots in developing countries, are especially poorly understood. Working in one such hotspot, the Indian Himalaya, we measured and modelled field-scale soil budgets, to quantify erosion-induced changes in soil carbon storage. In addition, we used long-term (1-year) incubations of separate and mixed soil horizons to better understand the mechanisms controlling erosion-induced changes in soil carbon cycling. We demonstrate that high rates of soil erosion did not promote a net carbon loss to the atmosphere at the field scale. Furthermore, our experiments showed that rates of decomposition in the organic matter-rich subsoil layers in depositional areas were lower per unit of soil carbon than from other landscape positions; however, these rates could be increased by mixing with topsoils. The results indicate that, the burial of soil carbon, and separation from fresh carbon inputs, led to reduced rates of decomposition offsetting potential carbon losses during soil erosion and transport within the cultivated fields. We conclude that the high rates of erosion experienced in these Himalayan soils do not, in isolation, drive substantial emissions of organic carbon, and there is the potential to promote carbon storage through sustainable agricultural practice.University of ExeterIndian Council of Agricultural Researc
International conference on Science and technology in archaeology and conservation
No full textMany bridges have been built in Lebanon, due to its geography of rivers and valleys. These bridges mostly belong to Roman, Mediaeval and Ottoman periods or to the French mandate. With modern urban development, new vacant transportation means such as highways appeared in Lebanon during the 1920s. These new roads crossed through the same passages as the old roads or bridges; sometimes they were parallel and sometimes overlapping. The historical variable bridges became residue and adjacent to the new highways. Large high-speed highways transformed the historical bridges into neglected elements of the landscape. Only a few bridges, belonging to the French mandate (1920-1945), are still used as vacant transportation means. This article presents a proposal to promote and enhance those remaining historical bridges. The proposal includes techniques to be used, including lighting and security system as well as restoration and consolidation interventions, the transformation process and the activity proposal. The author uses the Jaj Bridge to illustrate this proposal.N/A347-357, ill
On Combinatorics of Projective Mappings
No full textWe consider composition sets of one-dimensional projective mappings and prove that small composition sets are closely related to Abelian subgroups. 0 Introduction Freiman [5, 6] and Ruzsa [12, 13] studied subsets of R, for which jA+Bj Cn, where jAj = jBj = n. (They described the structure of A and B in terms of some natural generalizations of arithmetic progressions.) Using their theorems, Balog-Szemer'edi [1] and Laczkovich-Ruzsa [8] found some "statistical" versions. Their results extend to torsion-free Abelian groups, as well. Generalizations to non-Abelian groups were initiated by the first named author in [3, 4], where the one-dimensional affine group was considered. The goal of this paper is to find similar results for the (still one-dimensional) projective group. Throughout this paper P will denote the group of non-degenerate projective mappings of R, i.e., the set of non-constant linear fractions x 7! ax+b cx+d (where ad \Gamma bc 6= 0), with the composition as the group..
- …
